A word of warning:
DropBox, like SugarSync or Minus, etc., are very convenient 'clouds'. Convenient for syncing files, and transferring files. But NOT for storing files! Because you don't control access! DropBox, SugarSync, and Minus, etc., do! So if your only copy of a file is in the cloud it will one day be a very unpleasant surprise if the cloud is offline, for some reason, or if it is compromised by hackers, or if Messrs. DropBox, SugarSync, and Minus (and others of course) suddenly demand payment for you to access your own data !
So don't make your cloud your primary repository of your data. You never know who else has access to it. And you never know for sure if you will have access to it!
If you want to use your cloud to have copies of important personal files (passports, drivers license, insurance policies, deeds of sale, warranties, testaments, etc. etc.) available wherever you can access the internet then encrypt those files before you upload them to the cloud. So in case your cloud gets compromised by third parties they still have the file encryption to deal with.